Magnetron



Feb. 28, 1950 J. W. MCNALL 2z BY ATTORN EY 'Patented Feb.' 28.1950

MAGNETRON John W. McNall, East Orange, N. J., assigner to WestinghouseElectric Corporatiom-East Pittsburgh, Pa., a corporation of PennsylvaniaApplication vlune 15, 1944, Serial No. 540,453

(Cl. Z50-27.5)

11 claims. l

rihis invention relates to magnetrons and more particularly to tuningmeans therefor.

An object of the invention is to provide an improved and convenientmeans. for vtuning a magnetron.

Another .object is to .provide for a wide range of tuning fora-magnetron.

A further object is to provide a rotative or oscillatory tuning meansand 'with its taxis lof movement coincident with vthe axis of thecathode and anode.

A still further object of the invention .is to provide a simple, lightand .readily Iassembled rotor for the tuning 'mea-ns.

Further objects l'of the invention will appear to those skilled in theart to which it appertains both by direct recitation thereof as thedescription proceeds and by inference from the-context.

Referring to the accompanying drawing in which like numerals ofreference indicate like parts throughout the several views;

Figure 1 is a, cross section of 1a magnetron in which my invention isemployed, the section being taken just below the end plate andlongitudinally of the tuning control means.

Figure 2 is a section on 'line .II--II' oi Fig. 1;

Fig-ure 3 is a Icross section on line III-III ofv Fig. 2;

Figure 4 is a perspective view ofthe rotor con-V stituting an essentialpart of the' invention;

Figure 5 is a cross section of one of the rotor varies; and

Figure 6 is a cross section ofa modified construction of rotor vane.

In the specific embodiment of the invention illustrated invsai'ddrawing, the vreference numeral lli designates a. magnetron body portionshown as cylindrical, of metal, and closed by metallic end plates orcaps I I. The particular magnetron here shown provides a plurality-ofinternal radially disposed xed metallic venes I 2l ofi less length thanthe cylindrical interior of the' body portion so as to leave 'end spacesI3 between the ends of the vlanes and the end plates II. Said firedvanes have-'their inner longitudinal edgesseparated from each other anddirected toward', a cylindrical centralized cathode Il' having usualinternal heating filament I'51 The vanes converge toward each other,viewed from the exterior, and thus define between successive variesy ofthea-nnular series thereof cavities having approximately trapezoidalcross-sectional shape, .and for convenience of reference referred tolasthe resonant cavities I6. The region aroundthe cath-y ode 'and withinthe inner edges: of the several varies is herein designated the cathodecavity I1. The iixed vanes, and particularly the inner edges thereof,constitute the anode. Input for the lament I5 is by way of lead-instructures I8 of usual construction, and output for derived energy is byway of a coaxial line I9 which is shown having an appropriate loop 20 inone of the resonant cavities.

In carrying out the present invention, the tuningmeans includes a rotor,shown alone in Fig. 4, said rotor being fabricated with twoparallelrings 1l', which may be either of metal or oi insulator material,centeredA on a common axis, which in use is coaxial with the axis of thecathode and anode of the magnetron. When the rotor is assembled in themagnetron, said rings are within the aforementioned end spaces I3..Extending between the rings, in parallelism to the said axis, are aplurality oi metallic vanes 22 evenly spaced in an annular series and inradial planes, except that there may be omission of or modication of onevane of the rotor corresponding to the cavity having the output loop,but otherwise there is shown one vane on the rotor for each resonantcavity of the magnetron. The number of vanes employed.. however, may bevaried as desired.. The rotor vanes are carried atv their ends by andrevolved, with restricted amplitude, by the said rings. rotor vanes havethe same relation. to their respective resonant cavity walls at anygivenposition of the rotor, and rotation of the rotor makesv a correspondingchange of position for all of said rotor vanes with respect to the fixedvaries. For instance, one position of the rotor vanesis shown in solidlines in Fig. 3 and another position thereof is shown by adjacent dottedlines. Furthermore, the rotor vanes are free of contact from theycylindrical wall of the magnetron body, and havey ay width less thanthat of the xed varies so as not to project into the central or cathodecavity. The said rotor vanes are eachk likewise quite thin and may bemade with opposite faces parallel as shown in Figs. 1 to 5, or may be avane 22s,. which is tapered in cross section asf shown in Fig. 6, inwhich event the thicker edge is parallel toA and next the cylindricalwall of the body portion. If desired, the rotor vanes may be coveredwith a dielectric material, such as mica or glass, to increase thecapacity between rotor and 'fixed vanes andN prevent sparking therebetween.

The rotor has, as a part thereof, a spider mount at' eachend, each saidmount having a hub23 from the periphery of which radiate: sev*- erallwirelegs 2l?, outerfendportions of whiclrz are bent into parallelismwith the hub axis and in a direction toward the ring of the rotor. Theseend portions of said legs 24 are embedded in, riveted tc or otherwisesecured to the said ring. Preferably, the said legs are electricallydiscontinuous one from another to avoid setting up induction current ow,and are shown each embedded separately in the hub which is indicated asof insulating material. Projecting axially outward from the hub' 23 is apivot pin 25, the projecting end of which is shown seated in a bushing26 carried at the middle of the inner face of end plate or cap Il.

In order to rotatively adjust the rotor, either clockwise orcounterclockwise, a lever 21 is shown as having an inner forked endengaging the bent leg portion of one of said spider legs 24, said leverprojecting in a generally radial direction from engagement with said legto a distance outside of the magnetron body. Said lever, however, isenclosed within a housing 28 which includes a flexible portion 29 bywhich vacuum sealing of the magnetron interior is maintained butpermitting said lever to pass to the exterior and be there under controlof the operator.

Inasmuch as said lever must be held securely in adjusted position,retaining as well as adjusting means are provided for the purpose. Asshown, the lever has a head 3Q thereon to which ilexible housing portion2S is secured and also on which is secured a bracket 3i which provides aforked end laterally of the lever. A sleeve 32 extending in the samegeneral direction' as the lever is pivotally carried by saidv forked endso as to swing in the sameplane inl which the lever swings.Longitudinally through the sleeve, and in threaded engagement therewith,is an adjusting screw 33 having a ball and socket connection with abracket 34 fixed with respect to the magnetron. The outer end of theadjusting screw has a knurled'knob 35 or other convenient manipulationmeans.

It is believed the theory of tuning by shifting the rotor vanes intodifferent relations with respect to the xed vanes or cavity walls willbe in accordance with the following two possible explanations. closer toa fixed wall of the cavity resonator, the capacity between said wall andvane will be increased. Change of capacity will result in a change inthe resonant frequency of that cavity resonator, thereby changing thefrequency of the oscillations generated by the magnetron. Secondly, thetuning or rotor vanes and supporting ring or rings have a resonantfrequency so that oscillations which may be generated therein react withthe normal oscillations of the cavity resonators resulting in a changeof frequency of the latter oscillations, and hence of the oscil-.lations generated by the magnetron.

I claim:

Al. In a magnetron having a circular series of cavity resonators, andhaving intervening walls separating said resonators, tuning means forsaid magnetron comprising a vane within one of said resonatorsand'extending in the same genera-l direction as the said interveningwalls bounding that one'of said resonators and movable in its entiretyin parallelism to itself to closer proximity to one' intervening wallthan to the other intervening wall of the resonator in which said vaneis located.

2. In a magnetron-having a cavity resonator, tuning means comprising avane in said cavity resonator extending substantially from end to First,asa rotor vane is brought end of said resonator dividing the resonatorspace into two parts, means at an end of said resonator Cllr supportingsaid vane, said means being rotatable in a direction normal to the vanefor revolving said vane within the connes of said resonator and therebychanging the ratio of the two parts of the resonator space, andadjustable means in operative engagement with said vane supporting meansfor rotating said means and revolving said vane.

4. In combination with a magnetron having an axis and having a pluralityof cavity reso-'g nators longitudinallyparallel to the axis of themagnetron, tuning means therefor comprising a rotor having vanesdisposed longitudinally in said resonators parallel to said axis andsubstantially in planes with said axis, said rotor having limitedamplitude of rotation and all of said vanes being iixed in relation toeach other and simultaneously movable with correspondingly limitedamplitude in said resonators in which they are disposed.

. 5. Tuning means for a magnetron comprising a rotor having a ring, ahub coaxial with Ysaid ring, legs extending from said hub to said ring,

andv vanes xed on therewith.

6. Tuning means for a magnetron comprising a plurality of rings inspaced parallel planes and Centered on a common axis perpendicular tosaid planes, hubs offset outwardly from said planes and coaxial withsaid axis, legs connecting each hub with lone of said rings, and vanesextending longitudinally between said rings and fixed at their ends tosaid rings. y '7. Tuning means for a magnetron comprising a plurality of-rings in spaced parallel planes and centered on a common axisperpendicular to said planes, hubs oiset outwardly from said planes andcoaxial with said axis, coaxial pins on the hubs projecting outwardlyfrom each for rotative support thereof, legs connecting each hub withone of said rings, and vanes extending longitudinally between said ringsand fixed at their ends to said rings.

8. Tuning means for a magnetron comprising a plurality of rings inspaced parallel planes and centered on a common axis perpendicular tosaid planes, hubs of insulative material oiTset outwardly from saidplanes and coaxial with said axis, legs connecting each hub with one ofsaid rings, and` vanes extending longitudinally be-, tween said ringsand fixed at their ends to saidl rings. 1 v

9. In combination with an enclosure of an electron discharge device anda movable part within said enclosure, an operating mechanism. for saidmovable part comprising a housing projecting from and secured to saidenclosure, saidhousing having an opening longitudinally there-r through,a lever in and longitudinal of said open-4 ing and pivoted to saidhousing, a exible sleeve sealed at one endfto the housing and sealed atyits otherl end to the outer .end of the leven' thereby enablingvacuum-to be maintained said ring and rotatable said enclosure and housing andenabling said lever to be swung exterior to the housing and operate saidmovable part within the enclosure; L 10. In combination with anenclosure' of an .l

electron discharge device and a movable partij Within said enclosure, anoperating mechanism'vl for said movable part comprising a housing proingand pivoted to said housing, a flexible sleeveA sealed at one end to thehousing and sealed at its other end to the outer end ofthe lever,thereby,

enabling vacuum to be maintained in said en-k closure and housing andenabling said lever to be swung exterior to the housing and operate saidmovable part within the enclosure, and means at 11. In combination withan enclosure of ani electron discharge device and a movable partA meanspivoting said lever to the housing, and

means iexibly connecting the lever at an exteriorly projecting partthereof to said housing and providinga vacuum tight seal for the openingthroughjfthehousing, said flexible means enabling said lever to"`-beswung and at the same time maintain thevacuum therein and in the housingand enclosure.

JOHN W. MCNALL.

REFERENCES CITED The following references are of record in the le ofthis patent:`A

Within said enclosure, an operating mechanismA for said movable partcomprising a housing projecting from and secured to said enclosure, saidhousing having an opening therethrough, a lever in and projecting fromsaid opening of the housing into the interior of said enclosure and inoperative engagement with the part therein to be moved, and said leverprojecting to the exterior of said housing through said opening,

UNrrEDv STATES PATENTS Number Name Date 318,461 Gardiner May 26, 1885932,111 lFessenden Aug. 24, 1909 1,309,753 De Forest July 15, 19191,812,828 Gray; June 30, 1931 2,063,137 Whitenack Dec. 8, 1936 2,145,225Kolster et al Jan. V24, 1939 2,243,537 Ryan; May 27, 1941 2,281,717Samuel May 5, 1942 2,298,949 Litton Oct. 13, 1942 2,304,186 Litton Dec.8, 1942 2,323,735 Tawney July 6, 1943 2,356,414 Linder Aug. 22, 19442,391,016 Ginzton et al. Dec. 18, 1945 2,418,469 I-Iagstrum Apr. 8, 19472,424,496 Nelson July 22, 1947

